Regioselectivity in the reactions of bis-hydrazonoyl halides with pyrimidine-2-thiones

Bis-hydrazonoyl chlorides react regioselectively with pyrimidine-2-thiones, which contain a masked thiourea residue, to give the hitherto unknown anne lated 2,3-bis-arylhydrazono thiazoles and 3,3 ' -bis-1,2,4-triazoles. React ion of bis-hydrazonoyl chlorides with 2-methylthio derivatives gave only 3, 3 ' -bis-1 2,4-triazoles.